Many electronic system (e.g., mobile phones) comprise regulators which couple supply devices (e.g., batteries, main transformers) and consuming devices (e.g., transmitters, speakers, logic circuits, memories). The properties of the regulators are described, for example, by an input voltage V.sub.IN, an input current I.sub.IN, an output voltage V.sub.OUT, and an output current I.sub.OUT. According to a time scheme the regulator provides V.sub.OUT and I.sub.OUT within predetermined minimum and maximum values to the consuming device. A reverse action from the consuming device to the regulator is often not wanted but should be accommodated by the regulator. A regulator which uses energy effectively supplies V.sub.OUT and I.sub.OUT according to the needs the consuming components.
In a nonlimiting example of a mobile phone, the regulator receives V.sub.IN and I.sub.IN from a battery and provides V.sub.OUT and I.sub.OUT to a transmitter and to a memory. The transmitter sends radio signals in bursts (e.g., "operating mode A"). During a waiting time between the bursts (e.g., "operating mode B"), the regulator should recover from changes of V.sub.OUT caused by the transmitter. The waiting time is crucial for the performance of the mobile phone. While waiting, the regulator should consume only a low quiescent current (e.g., I.sub.IN); and the output voltage V.sub.OUT should stay above a minimum value required by the memory. Regulators for such applications are known in the art as low-drop-out (LDO) regulators.
The present invention seeks to provide regulators which mitigate or avoid disadvantages and limitations of the prior art.